NOW YOU can admit it: you were never really sure whether 12 a.m. meant noon or midnight, were you? The same for 12 p.m. You probably assumed, as we did, that everyone else had been taught which was which but you'd missed school that day. Thereafter, whenever someone said, "Meet you at 12 p.m. sharp," you were ashamed to ask what was meant. Usually you could assume it was noon, but perhaps there was one time when you couldn't afford to take a chance and so spent a half-hour standing outside a locked office building in the dead of night, just in case your boss showed up.

Well, now it turns out that nobody really knew what 12 a.m. and 12 p.m. meant, including all those people who acted as if they did. It took a dispute over the wording on a parking meter to bring the issue into focus. A motorist in Wildwood, N.J., assumed that since the meter was posted with the hours "8 a.m. to 12 p.m.," he could park free after noon. The judge ruled, in a remarkable display of loose construction, that the city fathers deemed 12 p.m. to mean midnight. The driver, however, was vindicated on appeal to a higher court, which said 12 p.m. could have meant either noon or midnight to the driver, or to anyone for that matter.

Federal authorities interviewed by the Associated Press agreed. "Technically, there is no such thing as 12 a.m. or 12 p.m.," said Joanne Petrie, a lawyer for the Department of Transportation. Gernot Winkler of the Naval Observatory called the terms 12 a.m. and 12 p.m. "inherently ambiguous."

But now that the problem has been identified and we can discuss it openly, what's to be done about it? The observatory recommends using simply "noon" and "midnight," which sound nice but probably wouldn't work in computer programs. Retired colonels and master sergeants will write us to urge adoption of the 24-hour military clock, but who wants to say, "I'll be down to get you in a taxi, honey, better be ready 'bout 2030 hours"?

One way or another the inherent ambiguity in the 12 a.m.-12 p.m. situation will be resolved, probably in the worst way imaginable, by the same people who compressed the names of the 50 states into two letters each. But it will take time and the work of many task forces. In the meantime, if you're caught spying in New Jersey, state it as your last wish that you be shot not at dawn, but at 12 p.m.